: TCC stuck OFF

05-18-04, 11:23 AM
Just went to a local Transmission shop to chase this code (P0741) on my 99 Eldorado and he tells me that the issue is most likely a solenoid inside the transmission failing.

He also mentions that to fix this requires the transmission to be pulled and he quoted me $800 to start.

He also said that it could be the actual Torque converter itself failing and to replace that would be equally as espensive and at that point, I may as well have the transmission rebuilt.

Anyone have this error before? Is there a cheaper way out?

05-18-04, 02:54 PM
Search in the archives for "TCC" or "VCC" and read up on how to diagnose.

You have a VCC by the way not a TCC but they operate in a similar fashion and the controls are very similar.

There is greater likelyhood that there is a problem outside the trans with the electrical circuit. The car supplies 12 volts thru the brake pedal switch to the trans and to the torque converter solenoid inside the trans. The "ground" side of the solenoid exits the trans and goes to the PCM. The PCM driver pulls the circuit to ground to apply the VCC.

To properly diagnose the entire circuit needs to be probed to make sure that the trans is receiving the 12 volts and than the ground circuit is going to the PCM and is being pulled to ground.

A proper shop with a GM Tech tool can commmand the VCC on and off to check the circuits and the trans operation. You can prob the connections for proper voltage and grounding. Even a misadjusted brake switch can cause the circuit to be broken and the VCC to be inoperative under some conditions.

I would thoroughly trouble shoot the circuit and have the controls looked at with a Tech tool before I would drop the trans to replace the VCC apply solenoid. If it is the solenoid it does require dropping the trans as the solenoid is under the side cover of the trans and the most feasible way to change the solenoid is by pulling the trans.. The fact is that it "could" be the solenoid, the wiring, the brake switch, a fuse, a connector, a wire, the trans, the torque converter, the PCM, etc..... No one can just look at the code and say. It has to be diagnosed.

VCC apply solenoids do fail....but rarely I would say. It would be even more rare for the torque converter to fail...it could but not likely. There is a detailed diagnostic procedure for this failure in the service manual that covers all this that would easily justify the cost of the service manual...the Helms manual...not a chiltons or something.

05-18-04, 07:23 PM
Awesome, thanks bbob! I've got the helm manuals, and will chase this down.

Funny that you say it's a VCC not a TCC. every OBD II code list I've seen calls P0741 "TCC Stuck off"

No matter, I definitely bow to your wisdom.

I will definitely be tracing some wires this weekend =)

One last question - I have not changed the trans. fluid at this point and the car does have 84K on it. I'm getting the fluid changed tomorrow because it can't hurt. However, the transmission guy I spoke with said a fluid change wouldn't resolve this issue. Any thoughts?


05-19-04, 11:50 AM
I would doubt that a trans fluid change will affect the problem. It is probably a waste of time and money at this point. The transfluid should be good for 100K easy unless you are towing a lot or something... I would get the manuals, diagnose the problem first, repair and then change the trans fluid if you don't end up dropping the pan or removing the trans otherwise....

05-19-04, 04:54 PM
I havn't researched this problem but a solenoid problem in my 4L60e was fixed with a fluid change. If it's a minor problem of a solenoid sticking from varnish or dirt there is a small chance of fresh fluid fixing it.

05-19-04, 10:32 PM
Funny that you say it's a VCC not a TCC. every OBD II code list I've seen calls P0741 "TCC Stuck off"

Read the previous posts in a search and there are several explainations of the difference between a VCC and TCC. You have VCC, trust me. The two actually perform the same function, to lock the torque converter to eliminate the slippage and improve the fuel economy. TCC is a direct lockup with no slippage. VCC has a viscous coupling in the mechanism so that it locks the converter in the exact same fashion but the viscous coupling will creep and minimize the torque pertubations in the drivetrain to enhance smoothness and eliminate chuggle. The diagnostic codes for TCC and VCC operate in similar fashions and the code numbers are the same as all OBD2 codes are standardized. To be specific, the codes are for TCC....VCC is a type of TCC. Read up in the service manuals. The VCC operation is very clearly described.